1. Field of Invention
This invention relates generally to laser-based bar code symbol reading systems, and more particularly to an automatic bar code symbol reading system having a compact, lightweight, laser scanning engine arrangable for mounting on the body of the user for hands-free scanning applications.
2. Brief Description of the Prior Art
Various types of laser scanning devices are in use and have been disclosed in the patent literature. Many of these scanners read bar codes, such as the Uniform Produce Code (UPC), which are imprinted on products, labels affixed to products, or packaging for products.
One type of scanner is referred to as a slot scanner. Typically slot scanners are counted beneath or at the checkout counter of a retail establishment, such as a supermarket. Another type of scanner is a hand-held scanner. This type of scanner typically includes a grip portion held in one's hand to enable the scanner to be directed onto a bar code so that the scan pattern produced by the scanner traverses the bar code symbol in order to read it.
In the last few years there has been increased development toward making hand-held scanners extremely small and lightweight. One such scanner is disclosed in my U.S. Pat. No. 4,930,848, whose disclosure is incorporated by reference, and which is assigned to the same Assignee as this invention. That scanner comprises a hand grip portion and a body portion. Within the body portion of the scanner is an "laser scanning engine" having all of the necessary optical, mechanical and electrical components required to produce a laser beam scanning pattern for reading bar codes and for receiving light reflected therefrom to produce an electrical signal indicative thereof. Other hand-held laser scanners are disclosed in the patent literature, including U.S. Pat. Nos. 4,387,297 (Swartz, et al.), 4,409,470 (Swartz, et al.), 4,460,120 (Swartz, at al.), 4,607,156 (Koppenall, et al.). 4,706,248 (Swartz, et al.), and 4,575,625 (Knowles).
Although prior art hand-held scanners are capable of reading bar code symbols, they all typically require that they be held in the hand of the user so that the laser beam scanning pattern can be aimed at the bar code symbol. In the course of checking out customers' purchases at a checkout counter, a clerk is thus required to continually pick up the scanner, direct its laser beam onto the symbols to effect the reading of the symbols, and then either lay down the scanner between readings or between customers or place it in a support cradle or mount so that the clerk can use his or her hands for other purposes.
Thus, there is a great need in the art for a bar code symbol reading system that offers the features of a hand-held system, while enabling hands-free triggerless operation.